[Users] Grid structure inconsistency & errors in surface mask locations

[Erik Schnetter]

On Mon, Apr 19, 2021 at 10:39 AM Konrad Topolski
<k.topolski2 at student.uw.edu.pl> wrote:
>
> I have been trying a variety of initial guesses, but to no avail.
>
> The setup is, in short:
> par_b = 3.0
> target_m_plus = 0.25
> target_m_minus = 0.75
>
> And the smaller black hole's apparent horizon gets detected easily, which cannot be said of the bigger one. My estimates for the AHFinderDirect were at -1.05 to -0.95 for the center of the ellipsoid/sphere, with initial guesses for the x_radius ranging from 0.25 to 0.4, with y_radius, z _radius about 10-20% smaller.
>
> Am I still not getting enough resolution? The refinement levels in my finest setup around x=-1 are:
>
> Carpet::max_refinement_levels    =8
> CarpetRegrid2::movement_threshold_1 =   0.16
> CarpetRegrid2::num_levels_2         =  8
> CarpetRegrid2::position_x_2         = -1.0
> CarpetRegrid2::radius_2[ 1]         =  64.0
> CarpetRegrid2::radius_2[ 2]         =  16.0
> CarpetRegrid2::radius_2[ 3]         =   8.0
> CarpetRegrid2::radius_2[ 4]         =   4.0
> CarpetRegrid2::radius_2[ 5]         =   3.0
> CarpetRegrid2::radius_2[ 6]         =   2.5
> CarpetRegrid2::radius_2[ 7]         =   2.0
> CarpetRegrid2::movement_threshold_2 =   0.16
>
> I do not know a-priori if this apparent horizon is best approximated by an ellipsoid (can one see this before performing the numerical simulation?) or not, but I don't know if I'm on the right track.
> It seems weird to me that I cannot find the x=-1 AH, even though the corresponding black hole it is ~3 times more massive.
>
> In another attempt, I tried to copy the philosophy of the setup in the GW150914.rpar file,
> setting the center_offset for the two punctures and other parameters, but that didn't work either.
> I took
> target_mp=0.75, target_mm=0.25,
> separation D=6, so xp=D*mm = 1.5, xm=D*mp=-4.5,
> par_b=D/2 = 3.0, center_offset=xp-half_D=-1.5
> (all here: https://gist.github.com/konrad-topolski/1c208415d3edac2f428ded637153f639)
> I'm starting to doubt if any of these setups is correct.
>
> By the way, can I somehow redirect the outputs of all MPI processes to one file at real time, better still, override the creation of CCTK_Proc files altogether?

No, this is not possible. This would be very expensive because it
would be necessary to lock this file for every output. However, since
this is just a test, you can run on a single MPI process.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>
http://www.perimeterinstitute.ca/personal/eschnetter/